This invention relates to a method of and apparatus for discriminating the colour of road markings, especially but not exclusively in the field of lane departure warning systems.
Lane Departure Warning (LDW) and other automotive guidance systems use optical cameras to view the road markings ahead. For economy, it is common practice to use a black and white (monochrome) camera.
In some countries, road works or other diversion lanes are marked in coloured paint and the original (generally white) lines are not deleted. Black and white LDW systems may find it hard to discriminate between the two. Distinguishing between white and other colour lines by using absolute intensity is susceptible to local changes in ambient light (such as shadows) and faded paint. It is therefore desirable to be able to detect the difference between different coloured road markings. Herein, “determining” should be read to include distinguishing between two or more different possible colours for a road marking.